DE10155583B4 - circuitry - Google Patents

Abstract

Circuit arrangement for reading switching signals into a sensor, wherein a control unit is provided for generating the switching signals, characterized in that the control unit (4) is followed by two computer units (6, 7), which are coupled for mutual function checking and synchronization, so that the specified one Switching signals having switching states are fed to both computer units (6, 7), with an activation signal being generated in each computer unit (6, 7) for each switching signal that the computer units (6, 7) have a number of coupling units (12a.) Corresponding to the number of switching signals , b) is arranged downstream, the activation signals of both computer units (6, 7) assigned to a switching signal being fed to the inputs of each coupling unit (12a, b), and the output of each coupling unit (12a, b) being connected to an input (3a, b ) of the sensor (2) is guided so that by applying a given combination nation of switching states of the activation signals on a coupling unit (12a, b) via which the switching state of the corresponding switching signal of the control unit (4) is fed into the sensor (2).

Description

The invention relates to a circuit arrangement according to the generic term of claim 1

Such circuit arrangements are used for Control of sensors used, typically via the respective circuit arrangement operating parameters of the sensor are specified. These operating parameters are entered into the sensor in order to Adapt operation to the respective application.

Such sensors, in particular Optical sensors are becoming common also used to protect hazardous areas on machines and systems. On example for Such optical sensors are surface distance sensors who monitors the apron of a machine, a vehicle or a system becomes. These area distance sensors have a distance sensor element which emits light beams emitted to detect objects. In addition, the area distance sensor a deflection unit, by means of which the transmitted light rays within an area be periodically distracted. You can then use the area distance sensor within the captured area Objects are located, i.e. a position is determined of objects.

Depending on the application, in which one such an area distance sensor is used predefined areas on vehicles, machines or systems are monitored become. According to the dimensions of such an area in the area distance sensor defines a protective field of a given size, which is a section of the swept by transmitted light beams area forms. Then with the area distance sensor detects whether an object enters the protective field. Once this is the Case is in the area distance sensor generates an alarm signal, which is preferably used for decommissioning the monitored Unity leads so in particular a hazard is excluded by a person entering the protective field.

For use in such safety-critical applications, in particular in the area of personal protection, the sensors have a two-channel Set up to achieve the required level of security.

However, this is problematic the reading of operating parameters in such sensors, as well already for the import process meets the required security level got to.

An example of reading in such operating parameters in sensors is the selection of different protective fields in surface distance sensors according to the DE 199 17 509 C1 , In the area distance sensors described there, several different protective fields can be stored in one evaluation unit.

To select a protective field are several switches over one supply line each connected to an input of the evaluation unit, a saved protective field is assigned to each input.

By pressing a switch a predetermined signal value at the assigned input, which corresponds to activation of the input. This will make the assigned saved protective field activated, the objects in this Protective field can be detected. For test purposes is an output of the evaluation unit a predefined signal value can be output on the feed lines, which in the fault-free case at the corresponding input of the evaluation unit pending.

By reading back the data from the evaluation unit The signal read out for test purposes is failsafe guaranteed by the signal read in by the respective switch.

However, this is in no way guaranteed that the switch itself is fail-safe and therefore safe Switch signals generated.

Should the area distance sensor for safety-critical Applications used particularly in the field of personal protection , it is necessary that not only the sensor itself but also the circuit arrangement for the selection of the protective fields meets the required security level.

In principle, this requirement thereby fulfilled be that for the selection of protective fields two-channel self-monitoring Controls, in particular PLC controls, are used. such However, controls are very expensive, which increases the cost of such Circuitry undesirable is high.

The US 5,218,196 relates to a device for ensuring the function of a circuit of a photodetector system. The photodetector system is designed in particular as a light curtain. This generates a sensor signal, which is processed in the circuit as an input signal. An output control signal is generated in the circuit with which, for example, a machine can be stopped. The circuit has a first computer unit in which the signal processing of the sensor signal for generating the output control signal takes place. A second computer unit is also provided, which monitors the function of the first computer unit. The second computer unit is designed as a watchdog microcontroller. This simulates sensor signals and deactivates the first computer unit if it shows a malfunction based on the simulation signals.

This device thus forms one two-channel sensor signal processing unit, whereby by internal Simulation of sensor signals Errors in signal processing uncovered can be. The problem of fail-safe reading in of external switching signals is not addressed there.

The DE 40 33 243 A1 relates to a circuit arrangement for controlling photoelectric components of a light barrier or the like. The components are controlled one after the other by means of a switching device in the multiplex method. A control device is provided to detect functional errors. Here, the photoelectric components are connected in matrix form to the outputs of decoders, which interact with processors which are independent of one another and form the control device.

The DE 298 07 121 U1 relates to a circuit arrangement for a safety light curtain with several channels, each channel having a light transmitter and light receiver. There are also two microcontrollers.

Each transmitter has two transmission components and every recipient has two receiving components, each of these two components of the Sender or receiver is connected to another microcontroller.

The invention has for its object a Circuit arrangement of the type mentioned in such a way that Switching signals safe and verifiable at low cost a sensor can be entered.

To solve this task are the Features of claim 1 provided. Advantageous embodiments and appropriate further training the invention are described in the subclaims.

The circuit arrangement according to the A control unit has reading in switching signals in a sensor to generate switching signals with specified switching states. The control unit is each followed by two computer units, which are coupled for mutual function checking and synchronization are. The switching signals are fed to both computer units. In each computing unit is for each switching signal generates an activation signal. The computing units is a number of corresponding to the number of switching signals Coupling units arranged downstream, each on the inputs Coupling unit the activation signals assigned to a switching signal fed both computing units are, and wherein the output of each coupling unit to an input of the sensor is. By applying a predetermined combination of switching states Activation signals on a coupling unit is via this the switching state of the corresponding switching signal of the control unit fed into the sensor.

The basic idea of the invention is the switching signals generated in a control unit via a Read circuit arrangement into a sensor, which two single-channel has constructed computer units. In each computing unit for a Switching signal generates an activation signal. The one switching signal assigned activation signals of the two computer units are used for Control of a coupling unit. Here are the activation signals chosen so that their switching states in a clear manner from the switching state of the assigned switching signal depend and at the same time are connected to the coupling unit that their output signal again the switching state of the switching signal delivers, which then over an input is read into the sensor. Through this two-channel Structure of the circuit arrangements according to the invention as well as by the mutual function check of the synchronized working Computer units are a safe and verifiable reading of the switching signals reached in the sensor.

The control unit is preferred from a controller, in particular a vehicle controller or one Machine control, formed. In general, the control unit can also be formed by a software module or by actuators.

Due to the single-channel structure of the Computer units, in particular designed as PLC controls are a cost effective Structure of the circuit arrangement according to the invention receive.

To synchronize the computing units this preferably about two synchronization services coupled via which synchronization signals be sent

In an advantageous embodiment, the sensor has monitored, fail-safe inputs as in FIG DE 199 17 509 C1 described on. In this configuration, the circuit arrangement according to the invention fulfills the safety requirements required for use in personal protection.

In a further advantageous embodiment According to the invention, the coupling units are designed as optocouplers and thus form a galvanically isolated interface to the sensor.

The mutual function check of the synchronized Computer units working preferably takes the form of dynamic ones Tests that are carried out at specified time intervals. there the switching state of an activation signal is in a first computer unit changed briefly and the corresponding change checked in the other computer unit. With this functional test can in particular, it is determined whether a computer unit is switching off may or may not.

The invention is set out below explained using the drawing. It shows:

1 Block diagram of an embodiment of the circuit arrangement according to the invention for reading switching signals into a sensor.

1 shows an embodiment of a Circuit arrangement 1 for reading switching signals into a sensor 2 ,

The sensor 2 is formed by an area distance sensor in the present exemplary embodiment. The area distance sensor has a distance sensor element (not shown separately) and a deflection unit (also not shown). The distance sensor element is used to determine the distances of objects using the runtime method. For this purpose, the distance sensor element has a transmitter that emits light rays and a receiver that receives light rays. The respective object distance is calculated from the transit time of the transmitted light rays directed to an object and from the received light rays reflected back by the object. With the deflection unit, the transmitted light beams are periodically deflected in a scanning plane. The detection of the current angular positions of the transmitted light beams and the associated distance values enables objects to be located within the scanning plane.

The area distance sensor monitors whether an object penetrates a specified protective field. The protective field forms a defined section of the scanning plane. As soon as an intrusion of an object into the protective field is registered, the sensor 2 generates a scanning signal. The sensor 2 is used in particular in the area of personal protection for monitoring hazardous areas. Accordingly, the evaluation unit of the sensor 2 , in which the signal evaluation of the distance sensor element takes place, has a redundant, two-channel structure.

Depending on the application, it may be necessary to use the sensor 2 Detect objects within different protective fields. Therefore are in the sensor 2 several protective fields and their geometries are saved. In the present case, there are two different protective fields in the sensor 2 stored.

One of these protective fields is selected according to the respective application, so that within this protective field with the sensor 2 Objects are detectable.

To select the respective protective field, the saved protective fields are each an input 3a, b of the sensor 2 assigned. In the present case, the sensor points 2 two fail-safe inputs 3a, b to select the protective fields.

The respective protective field is selected via a control unit 4 , In the simplest case, the control unit exists 4 from a number of actuators, in particular switches, by means of which the desired protective field can be selected. Alternatively, the control unit is formed by a machine or vehicle control. In general, a software module that is integrated in controls or the like can take over the function of the control unit. The control unit points in accordance with the number of protective fields to be selected 4 two outputs 5a, b , via which a binary switching signal is output. Each switching signal has two switching states "on" and "off".

About that of the control unit 4 downstream circuit arrangement 1 is a switching signal to an input 3a, b of the sensor 2 guided. With the control unit 4 a protective field is selected by operating the control unit 4 the corresponding switching signal is set to the "on" switching state, while the other switching signals assume the "off" switching state. This ensures that in the sensor 2 only one protective field is selected and activated.

To meet the safety requirements, in particular for use in personal protection, the control unit instructs 4 Subordinate switch arrangement has an essentially two-channel structure, so that by means of this a fail-safe reading of the switching signals into the sensor 2 is guaranteed.

The circuit arrangement 1 has two computing units 6 . 7 on, which are designed in particular as PLC controls. The computing units 6 . 7 have a single-channel structure and are advantageously identical.

Every switching signal at one output 5a, b the control unit 4 is each in an entrance 8a, b . 9a, b each computing unit 6 . 7 read. In every computing unit 6 . 7 a binary activation signal is generated for each switching signal. The binary activation signal has the switching states "high" and "low".

The activation signals in each computing unit 6 . 7 are generated via a separate input / output 10a, b . 11a, b the respective computer unit 6 . 7 read. Each input / output has a directional circuit, by means of which the input / output can be operated as both an input and an output.

Such an input / output is used to output an activation signal 10a, b . 11a, b operated as an output. An input / output is used especially for test purposes 10a, b . 11a, b operated as an entrance.

Alternatively, instead of inputs / outputs Circuits with separate inputs and outputs be provided.

The activation signal at an input / output 10a, b the first computer unit 6 and the activation signal at an input / output 11a, b the second computer unit 7 , which are each assigned to a switching signal, become a coupling unit 12a, b fed. In the present case there are two identical coupling units designed as optocouplers 12a, b intended.

The activation signals of the computer units assigned to a switching signal 6 . 7 are fed to the assigned optocoupler via a resistor network. The resistor network comprises several resistors 13 - 17 , where a Wi resistor 15 this network is connected in parallel with the optocoupler. This resistance 15 forms a bypass resistor that ensures that at the assigned inputs / outputs 10a, b . 11a, b the computing units 6 . 7 a defined voltage level is present, even if no current flows through the optocoupler.

The outputs of the coupling units 12a, b are on one entrance each 3a, b of the sensor 2 guided. Furthermore, each coupling unit 12a, b to a supply voltage potential and via a resistor 18 to a ground connection of the sensor 2 connected.

The computing units 6 . 7 are on two synchronization lines 19 . 20 coupled. Here are the synchronization lines 19 . 20 at inputs / outputs 10c, d . 11c, d of the computer units connected. Synchronization signals are sent via the synchronization lines, causing the computing units 6 . 7 operated synchronously.

The inputs / outputs 10a, b . 11a, b the computing units 6 . 7 are each routed to the assigned optocoupler in such a way that current can only flow through it when the activation signal of the first computer unit 6 assumes the switching state "high" and at the same time the activation signal of the second computer unit 7 assumes the switching state "low". This assignment of the switching states of the activation signals corresponds to the switching state "on" of the assigned switching signal. Due to the current flow in the optocoupler, this switching state is transferred to the assigned input 3a, b of the sensor 2 read.

The switching state "off" of a switching signal is in the activation signals of the subordinate computer units 6 . 7 encoded in such a way that the activation signal of the first computer unit 6 the switching state "low" and the activation signal of the second computer unit 7 assumes the switching state "high". Alternatively, both activation signals could assume the switching state "low" or both activation signals the switching state "high". In any case, no current flows through the assigned optocoupler. The output signal at the optocoupler output corresponds to the switching state "Off" of the switching signal, which in the corresponding input 3a, b of the sensor 2 is read.

Thus, by mapping the switching states of the switching signals to the switching states of the activation signals and the subsequent generation of the output signal of the respectively assigned optocoupler, which clearly depends on the switching states of the activation signals at its input, the switching state of the switching signal at the output of the optocoupler is recovered and into the computing unit 6 . 7 read.

To check the functionality of the computing units 6 . 7 dynamic testing is carried out at specified time intervals. The functional test is expediently carried out within two separate cycles. The first computer unit checks in a first cycle 6 whether the second computing unit 7 the shutdown function of the first computer unit 6 is intact. The function check is carried out in such a way that in a computer unit 6 an activation signal is changed, the change in the other computer unit 7 is registered. The second computer unit checks in a second cycle 7 correspondingly the shutdown function of the first computer unit 6 ,

The implementation of such a functional test is based on the example below with reference to 1 explained.

The function check is carried out in the event that only the first switching signal at the output is selected to select the first protective field 5a the control unit 4 assumes the switching state "on". Accordingly, the assigned activation signal points at the input / output 10a the first computer unit 6 the switching state "high" and the assigned activation signal at the input / output 11a the second computer unit 7 the switching state "low".

The first cycle of the functional test is carried out via the first computer unit 6 triggered in which a start signal to the second computer unit via the synchronization lines 7 is sent. At the same time, the first computer unit switches 6 the entrance / exit 10a on input operation. The second computer unit changes with the start signal 7 the switching state of the activation signal at the input / output 11a from "low" to "high". The resulting change in level is at the input / output switched to input mode 10a the first computer unit 6 registered and evaluated. In error-free operation there must be a signal change at the input / output 11a corresponding level change can be registered.

The second cycle of the functional test is carried out via the second computer unit 7 triggered in which a start signal to the second computer unit via the synchronization lines 7 is sent. The second computer unit switches at the same time 7 the entrance / exit 11a on input operation. The first computer unit changes with the start signal 6 the switching state of the activation signal at the input / output 10a from "low" to "high". The resulting change in level is at the input / output switched to input mode 11a the second computer unit 7 registered and evaluated. In error-free operation there must be a signal change at the input / output 10a corresponding level change can be registered.

This in 1 The exemplary embodiment shown relates to an arrangement for selecting two protective fields, two coupling units being used for this purpose 12a, b are provided.

This arrangement can be expanded so that several protective fields are selected can be. A circuit arrangement for selecting four protective fields is particularly preferred. In this case, four coupling units are provided, the number of inputs and outputs of the control unit 4 , the computing units 6 . 7 and the sensor 2 is adjusted accordingly.

1

circuitry

2

sensor

3a, b

entrance of the sensor

4

control unit

5a, b

outputs

6

first computer unit

7

second computer unit

8a, b

entrance (the first computer unit)

9a, b

entrance (the second computer unit)

10a, b

An exit (the first computer unit)

10c, d

An exit (the first computer unit)

11a, b

An exit (the second computer unit)

11c, d

An exit (the second computer unit)

12a, b

coupling unit

13-17

resistors

18

resistance

19

synchronization line

20

synchronization line

Claims (20)

Circuit arrangement for reading switching signals into a sensor, a control unit being provided for generating the switching signals, characterized in that the control unit ( 4 ) two computing units ( 6 . 7 ), which are coupled for a mutual function check and synchronization, are subordinate to the switching signals which have the predetermined switching states, in each case both computer units ( 6 . 7 ) are supplied, with each computer unit ( 6 . 7 ) an activation signal is generated for each switching signal that the computer units ( 6 . 7 ) a number of coupling units corresponding to the number of switching signals ( 12a, b ) is subordinate, with the inputs of each coupling unit ( 12a, b ) the activation signals of both computer units assigned to a switching signal ( 6 . 7 ) and where the output of each coupling unit ( 12a, b ) to an entrance ( 3a, b ) of the sensor ( 2 ) is performed so that by applying a predetermined combination of switching states of the activation signals to a coupling unit ( 12a, b ) the switching state of the corresponding switching signal of the control unit ( 4 ) in the sensor ( 2 ) is fed. Circuit arrangement according to claim 1, characterized in that the switching signals of the control unit ( 4 ) have binary switching states "on" and "off", which in the computer units ( 6 . 7 ) are converted into binary activation signals with switching states "high" and "low", the switching states of a switching signal unambiguously referring to predetermined switching states of the assigned activation signals in both computer units ( 6 . 7 ) are shown. Circuit arrangement according to claim 2, characterized in that each switching state of a switching signal is a switching state combination of assigned activation signals corresponds. Circuit arrangement according to one of Claims 1-3, characterized in that a selection of operating parameters of the sensor ( 2 ) he follows. Circuit arrangement according to claim 4, characterized in that the sensor ( 2 ) is formed by a surface distance sensor, by means of which objects can be detected within a protective field. Circuit arrangement according to Claim 5, characterized in that a plurality of protective fields are stored as the operating parameters in the area distance sensor, and that by means of the control unit ( 4 ) one of the saved protective fields can be selected, objects being detected within the selected protective field. Circuit arrangement according to claim 6, characterized in that the switching signals via separate outputs ( 5a, b ) the control unit ( 4 ) are output, with one output ( 5a, b ) via one input each ( 3a, b ) of the sensor ( 2 ) a protective field in the sensor ( 2 ) assigned. Circuit arrangement according to Claim 7, characterized in that, in the event of error-free operation, only one switching signal at the outputs ( 5a, b ) the control unit ( 4 ) assumes the switching state "on", whereby the protective field in the sensor assigned to the switching signal ( 2 ) is selected. Circuit arrangement according to one of claims 1-8, characterized in that the computer units ( 6 . 7 ) are each formed by a PLC control. Circuit arrangement according to one of claims 1-9, characterized in that the computer units ( 6 . 7 ) for synchronization via two synchronization lines ( 19 . 20 ) are connected, via which synchronization signals are sent be det. Circuit arrangement according to claim 10, characterized in that the synchronization lines ( 19 . 20 ) at inputs / outputs ( 10c, d . 11c, d ) the computing units ( 6 . 7 ) are connected. Circuit arrangement according to one of claims 1-11, characterized in that the coupling units ( 12a, b ) are each formed by an optocoupler. Circuit arrangement according to claim 12, characterized in that the activation signals of the computer units ( 6 . 7 ) are routed via a resistor network to the respective optocoupler, the resistor network having a bypass resistor connected in parallel with the optocoupler. Circuit arrangement according to claim 12 or 13, characterized in that the activation signals via inputs / outputs ( 10a, b . 11a, b ) the computing units ( 6 . 7 ) are fed to the respectively assigned optocoupler. Circuit arrangement according to one of claims 1-14, characterized in that the mutual function test of the computer units ( 6 . 7 ) takes place during predetermined time intervals, with a computer unit ( 6 . 7 ) the switching state of at least one activation signal is changed, and this change in the other computer unit ( 7 . 6 ) is checked. Circuit arrangement according to Claim 15, characterized in that the functional test is divided into two cycles, the first computer unit ( 6 ) the shutdown function of the second computer unit ( 7 ) and, during the second cycle, the second computer unit ( 7 ) the shutdown function of the first computer unit ( 6 ) checks. Circuit arrangement according to claim 16, characterized in that a cycle of a functional test by a first computer unit ( 6 ) by sending synchronization signals to the other computer unit ( 7 ) is triggered, whereby in the other computing unit ( 7 ) the switching state of at least one activation signal is changed, this change in the first computer unit ( 6 ) is checked. Circuit arrangement according to claim 17, characterized in that at an input / output ( 11a, b ) of the second computer unit ( 7 ) Pending, changed activation signals via the input / output ( 10a, b ) of the first computer unit ( 6 ), via which the assigned activation signal can be output, into the first computer unit ( 6 ) is read. Circuit arrangement according to claim 18, characterized in that the input / output ( 10a, b ) of the first computer unit ( 6 ) for reading in the changed activation signal of the second computer unit ( 7 ) is switched to input mode when the function test cycle is triggered. Circuit arrangement according to one of claims 1-19, characterized in that the control unit ( 4 ) is formed by a control, in particular a vehicle control or a machine control, a software module or actuators.